Passenger seats of automobiles or trains, various kinds of sofas, office chairs and the like are often formed by attaching a skin material such as fiber fabric or natural or synthetic leather to a surface of a cushion body (foam body) molded in a predetermined shape by using a foam resin material. The cushion body used in these various seats often has a curved surface composed of convex-concave shapes satisfying human engineering factors in order to maintain a seating posture which provides no fatigue despite long-hour seating.
Moreover, when the skin material is attached to the surface of a cushion body, after molding the cushion body in a desired shape, a method of covering and fixing the skin material to the surface of the obtained cushion body is often employed. In particular, in this case, a molded surface fastener is generally used as means for fixing the surface of the cushion body and a bottom surface of the skin material.
A molded surface fastener has a configuration in which a plurality of engaging elements (for example, male engaging elements) are disposed on one surface (first surface) of a base portion made of a thermoplastic resin, and such a molded surface fastener is integrated so that the engaging elements are exposed to the surface of the cushion body when the cushion body is molded. Moreover, a plurality of female engaging elements (loop-shaped engaging elements) configured to be fastened to the engaging elements of the molded surface fastener are formed on the bottom surface of the skin material that covers the cushion body.
After the skin material covers on the cushion body to which the molded surface fastener is integrated, the female engaging elements disposed on the bottom surface of the skin material are pressed against the male engaging elements of the molded surface fastener disposed on the surface of the cushion body, thereby the skin material is fastened to the molded surface fastener. In this manner, the skin material is easily fixed to the surface of the cushion body along the convex-concave shapes of the surface, and the skin material is prevented from floating from the cushion body.
Examples of the molded surface fastener integrated to the cushion body are disclosed in Japanese patent Publication No. 2002-78512 (Patent Document 1) and International Publication WO2003/030672 Pamphlet (Patent Document 2).
Here, a molded surface fastener described in Patent Document 1 is explained briefly referencing FIG. 20. The molded surface fastener 80 in Patent Document 1 is foamed by injection molding or extrusion molding of thermoplastic resin and configured by providing an engaging region 82 and a space region 83 alternately in a length direction on a thin plate-shaped substrate portion 81.
Each engaging region 82 of the molded surface fastener 80 has a plurality of hook-shaped engaging elements 84 standing on an upper surface of the substrate portion 81 and a continuous fence portion 85 which appears as a square shape or an oblong shape from a planar view and is formed by surrounding a plurality of the engaging elements 84. Left and right side edge attaching portions 86 whose upper surfaces are formed to be flat are disposed on the left and right outer side of the fence portion 85. Further, each space region 83 is provided between front and bottom engaging regions 82, and the upper surface of the space region 83 is formed as a flat surface in which the engaging elements 84 do not exist.
In a case of foam molding of a cushion body so as such a molded surface fastener 80 as in Patent Document 1 to be integrated to, the molded surface fastener 80 is held at an inner surface (cavity surface) of a molding die for molding the cushion body and a foam resin material is injected into an inner space (cavity) of the molding die. In this case, the upper surface (top end surface) of the fence portion 85 provided on the molded surface fastener 80 is closely contacted to the inner surface of the molding die, thereby an engaging element forming region which is in an inner side of the fence portion 85 and in which a plurality of engaging elements 84 are formed can be blocked from the inner space of the molding die.
Accordingly, by foam molding of the cushion body in a state that the fence portion 85 of the molded surface fastener 80 is closely contacted to the inner surface of the molding die, it is prevented that the foam resin material intrudes into the engaging element forming region beyond the fence portion 85, and the cushion body to which the molded surface fastener 80 is integrated in a state that the engaging elements 84 are exposed outside can be manufactured.
Particularly, in the molded surface fastener 80 in Patent Document 1 shown in FIG. 20, a space region 83 without having the engaging elements 84 is disposed between the adjacent engaging regions 82. Owing to this, in foam molding of the cushion body so as the molded surface fastener 80 in Patent Document 1 to be integrated to, the foam resin material easily flows into the space region 83 of the molded surface fastener 80 and foams and solidifies as surrounding the space region 83.
Owing to this, in the cushion body to which the molded surface fastener 80 is integrated, not only all the engaging elements 84 of the molded surface fastener 80 can be exposed outside but also an attachment strength (fixing strength) of the molded surface fastener 80 with respect to the cushion body can be effectively enhanced since the space region 83 is buried into the cushion body.
On the other hand, in Patent Document 2, a molded surface fastener which is characterized in that it has a thin plate-shaped substrate portion, at least one engaging element disposed on the substrate portion and a magnetic material mixed in the substrate portion in the length direction is described.
The molded surface fastener explained as an Embodiment in Patent Document 2 is shown in FIG. 21. The molded surface fastener 90 shown in FIG. 21 is configured by providing an engaging region 92 and a space region 93 alternately in the length direction at a center part of a thin plate-shaped substrate portion 91 in a width direction. Moreover, a magnetic body not shown in the Figures is mixed in a part of the region of the substrate portion 91 in the width direction along the length direction.
Each engaging region 92 of the molded surface fastener 90 has a plurality of hook-shaped engaging elements 94 standing on an upper surface of the substrate portion 91 and a continuous surrounding wall portion 95 which is formed as surrounding a plurality of the engaging elements 94 and appears as a square shape or an oblong shape from a planar view. Further, each space region 93 is disposed between the adjacent engaging regions 92, and the upper surface of each space region 93 is formed as a flat surface in which the engaging elements 94 do not exist.
Moreover, vertical resin intrusion barrier portions 96 are provided on respective left and right side edge parts of the substrate portion 91 along the length direction so as to interpose the engaging region 92 and the space region 93. Particularly in the molded surface fastener 90 shown in FIG. 21, each left and right vertical resin intrusion barrier portion 96 has four lines of vertical wall portions parallel to the length direction, and each vertical wall portion is formed by a plurality of vertical wall pieces standing on the substrate portion 91 at a predetermined interval with each other along the length direction. Further in the vertical wall portions adjacent to each other in the width direction, positions of the vertical wall pieces are moved alternately in the length direction, thereby positions of gaps formed between the vertical wall pieces do not overlap in the width direction.
In a case of manufacturing such a molded surface fastener 90 as in Patent Document 2, a manufacturing apparatus which has a cylinder-shaped die wheel capable of rotating in one direction and an extrusion portion extruding a foam resin material toward a periphery of the die wheel is used. Cavities (space portions) for molding an engaging element 94, a surrounding wall portion 95 and a vertical resin intrusion barrier portion 96 in a predetermined shape are provided on the periphery of the die wheel of the manufacturing apparatus.
Further, a storage portion storing a magnetic resin material containing magnetic powder, an extrusion nozzle extruding the magnetic resin material onto an extrusion surface of an extrusion portion, a flow channel flowing the magnetic resin material stored in the storage portion toward the extrusion nozzle are provided in the manufacturing apparatus. Owing to this, it becomes possible that the magnetic resin material is extruded from the extrusion nozzle at the same time of extruding the molten resin material from the extrusion portion, then the magnetic powder is mixed in a predetermined part of the molten resin material.
Generally, in the manufacturing apparatus of the molded surface fastener 90 as described above, a pickup roller is disposed opposing to a periphery of the die wheel on a downstream side of the extrusion portion for the molten resin material and the extrusion nozzle for the magnetic resin material in a rotation direction of the die wheel. By having the pickup roller, the molded surface fastener 90 formed by solidifying the molten resin material on the periphery of the die wheel can be peeled off and collected. By using such a manufacturing apparatus, the molded surface fastener 90 shown in FIG. 21 can be manufactured continuously.
Then, the cushion body is foam molded by injecting the foam resin material into the molding die in a state that the manufactured molded surface fastener 90 is held on a cavity surface of the molding die for molding the cushion body, thereby the cushion body to which the molded surface fastener 90 is integrated can be obtained.
In this case, in the left and right vertical resin intrusion barrier portions 96 provided on the molded surface fastener 90, though there is a possibility that the foam resin material intrudes, for example from a gap between the vertical wall pieces of the first line of the vertical wall portion disposed at the most outside of the vertical resin intrusion barrier portion 96 in foam molding of the cushion body, it can be prevented that the foam resin material intrudes into the engaging region 92 or the space region 93 of the molded surface fastener 90 beyond all four vertical wall portions forming the vertical resin intrusion barrier portion 96 since the vertical wall pieces among the vertical wall portions adjacent to each other of the vertical resin intrusion barrier portion 96 are disposed to be staggered each other as described above.
That is, in the molded surface fastener 90 shown in FIG. 21, the intrusion of the foam resin material into a forming region of the engaging elements 94 surrounded by the surrounding wall portion 95 is effectively prevented in foam molding of the cushion body by the left and right vertical resin intrusion barrier portions 96 provided on the left and right side edge part of the substrate portion 91 and the surrounding wall portion 95 provided in each engaging region 92.